It is known that transformers for energy transmission, for example, at a voltage level of 10 kV to 110 kV and above, can produce core losses in continuous operation. These losses can be ascribed to the re-magnetizing losses and hysteresis losses of a known laminated iron core and can cause a heating thereof. In order to reduce these undesirable losses, transformers which can reduce core losses have recently been built with cores made of an amorphous material.
However, the use of amorphous materials involves new designs and working methods as larger core cross sections may be used due to the lower flux density compared with a known transformer core. An amorphous core material can be more sensitive to higher temperatures than a grain-oriented core plate.
Transformer cores of this kind can be manufactured from a thin amorphous strip material which is arranged in a plurality of layers, for example several thousand, concentrically around one or more winding windows. One lamination usually covers one layer, for example, a circular angle of about 360°. A small overlap can be implemented, if desired. A supporting structure can be useful here, by which the core structure can be stabilized. In addition, the amorphous material, which can be available as a flat strip material, can be mechanically sensitive. The available widths of the strip material can be limited, for example to 200 mm. This can also restrict the sizes of a transformer core which can be realized mechanically. Therefore, in order to realize larger amorphous transformer cores, a plurality of congruent transformer core discs, the width of which can be limited by the width of the available strip material, can be arranged adjacent to one another and joined to one another.
However, cooling of the core can be more important with amorphous cores than with cores made of grain-oriented core plate, as the saturation induction, and therefore the nominal induction, can be dependent on the operating temperature. The possible nominal induction can decrease with increasing temperature. This can then be compensated for by an increased use of material.